The present invention relates to a metal plate having reinforced beads for a metal gasket.
An internal combustion engine is provided with a plurality of holes therein, such as cylinder holes, water holes, oil holes, push rod holes, and so on. Some of the holes must be securely sealed therearound to prevent fluid from leaking from the holes. Therefore, a gasket to be installed between two engine blocks must have good sealing ability around the holes of the engine.
A steel laminate gasket is formed of a plurality of steel plates. In order to securely seal around the holes of the engine, it is conventional that at least one of the metal plates of a steel laminate gasket is provided with beads around portions to be sealed. When the steel laminate gasket is tightened, the steel laminate gasket with beads as stated above operates fine as intended.
In a steel laminate gasket, sometimes, areas to be sealed are located very close to each other. In this situation, it is impossible to separately or independently form beads, so that adjacent beads are combined and a common portion of the beads is deleted. In some situations, also, one side of a sealing area is sealed by one bead, while the other sides are sealed by two beads, wherein two beads extend from one bead. Namely, in some situations, beads intersect with each other and an intersecting portion is formed.
When two beads intersect, an area of the intersecting portion of the two beads becomes large. Namely, a wide bead portion is formed at the intersecting portion. Therefore, when the steel plate with the intersecting portion of the beads is compressed, the intersecting portion of the beads shows a surface pressure weaker than the rest of the beads. When high pressure is applied, it is liable to leak at a weak surface pressure portion. As a result, a steel laminate gasket having a steel plate with an intersecting portion of the beads is not suitable for an engine requiring high sealing pressure.
Similarly, in case a metal gasket is formed of one metal plate, which is provided with an intersecting portion of beads, the intersecting portion becomes large. As a result, when the metal plate is compressed, the surface pressure at the intersecting portion of the beads becomes weaker than that at the rest of the beads. The metal gasket is, therefore, liable to cause leakage.
In this respect, Japanese Patent Publication (KOKAI) No. 58-149467 discloses that in case two beads intersect, the width of one bead is gradually reduced at the intersecting portion to thereby strengthen the intersecting portion. This structure is fine as long as no high pressure is applied to the reduced portion of the bead at the intersecting portion.
However, this sealing structure is not suitable in case high pressure is applied to the reduced portion of the bead. This is because the sealing ability is reduced if high pressure is applied to the reduced portion of the bead. A high pressure side of a bead must have a smooth surface.
Accordingly, one object of the present invention is to provide a metal plate for a metal gasket, which can provide high surface pressure throughout the entire bead, when compressed.
Another object of the present invention is to provide a steel plate as stated above, in which an intersecting portion of the beads has strength substantially equal to or stronger than the rest of the beads.
A further object of the present invention is to provide a steel plate as stated above, which can securely seal around a high pressure area.
A still further object of the present invention is to provide a steel plate as stated above, which can be used as one of metal plates of a steel laminate gasket.
Further objects and advantages of the present invention will be apparent from the following description of the invention.